Underbridge Catalog

5:06 Note: In all concrete drilling, do not drill through steel reinforcing bars. If steel is encountered, move bolt holes equally to avoid the steel. Plug the unused hole with concrete. 5:07 Mounting supports on steel structures where drilling is permitted (or on a special steel structural member provided). Drill 13/16” holes at the prescribed centers. 5:08 Installation of supports where drilling is prohibited. Several clamping methods can be used. Obtain exact dimensions of the structural members and contact Osburn Associates, Inc. for suggestions. 5:09 Special Attachment Arrangements. In many cases hardware may be custom designed and fabricated to solve attachment problems. When this is done, the system must be engineered to be compatible with the attachment arrangements. 5:09.1 Osburn Associates, Inc. can supply a range of special channels and fittings that can be used in most of these cases. These structural compo- nents provide wide design latitude, required strength and easy, on-the-job assembly.

6.02 Intermediate hangers transfer these forces at two points. (1) The attachment bolts. (2) The longitudinal bracing. 6.03 Anchor-Point experience the same loading as Intermediate type supports except forces due to friction. These units must also be able to withstand the following additional stresses: (1) Cable-pulling force (longitudinal). Because this is the only point where the conduit is restrained, it is also the point where resistance to cable pulling will be transferred to the supports from the conduit. Also, if the cable were to become hung up in the conduit run, the entire cable-pulling force would be applied to the conduit and transferred to this anchor point. (2) Longitudinal strand loads are also imposed on anchor point supports when stranding is used to brace intermediate hangers. The total longitudi- nal stranding load will be the summation of the intermediate loads on the strand. 6.04 Angle Bracing The purpose of the angle bracing is to enable supports to resist the forces developed from expansion and contraction, cable pulling and longitudinal stranding. Note: Heavy duty angle bracing available. 6:04.1 Angle bracing is required on both sides of all Anchor Point Sup- ports. (See Figure 13) 6:04.2 Anchor Point supports are used at the following locations: (1) Conduit expansion joints (2) Fixed points where conduit is restrained with stop rings Exceptions: Angle bracing is not required where the support is not stranded, is close coupled and not more than two conduits high.

VI. Bracing GENERAL There are two types of bracing: (1) Angle bracing shown in Figure 11 (2) Longitudinal bracing shown in Figure 12

FIGURE 11

anchor point hanger

FIGURE 13

strut bolted to threaded insert in bridge deck

intermediate

2” X 2” frame member

strut

various styles of adjustable braces are available

The following is a guide for the use and installation of these types of braces. Braces and strands should be sized according to loads imposed on the sup- ports.

For a schematic drawing of these forces, also see Figure 12

strand clamp

6.01 Intermediate Conduit Supports experience primarily three different loadings: (1) Loads in vertical direction from the weight of the conduit, cable and hangers. (2) Load in transverse direction imposed by wind (3) Load in longitudinal direction imposed by the frictional force developed by the expansion and contraction of the conduit.

anchor point

note: angle and longitudinal strand bracing should be installed on both sides of supports when bracing is required.

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